Mechanical linkage for generating a curved surface



Aug. 2, 1966 D. s. CHISHOLM 3,263,516

MECHANICAL LINKAGE FOR GENERATING A CURVED SURFACE Filed Sept. 10, 1965 ,2 SheetsShee-t 1 INVENTOR. 00 ug /as S. Chis/2o lm HTTORNEY Aug. 2, 1966 D. s. CHISHOLM 3,263,516

MECHANICAL LINKAGE FOR GENERATING A CURVED SURFACE 2 Sheets-Sheet 2 Filed Sept. 10, 1965 INVENTOR. Doug/a: 5. 65/155 a/m United States Patent 3,263,516 MECHANICAL LINKAGE FOR GENERATING V A CURVED SURFACE Douglas S. Chisholm, Midland, Mich, assignor to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed Sept. 10, 1965, Ser. No. 486,312 7 (Ilaims. (Cl. 74-105) This invention relates to an improved mechanical linkage. It more particularly relates to an improved mechanical linkage capable of positioning a point on a predetermined curved line or surface.

Frequently in the construction of buildings having curved surfaces it is desirable to provide a guide or a tool which is readily positionable on or adjacent to the building structure in such a manner that the required design is adhered to. In cases of circular or spherical structures this is readily accomplished, for example, by pivoting an arm on the center of the desired structure. However, oftentimes it is desirable to generate structures wherein there is no ready access to the center. For example, in a spherical or spheroidal dome often a suitable geometric center is not available or in the case of a dome having an elliptical cross sectional configuration the centers of generation may be remote and inaccessible such as being positioned well within the earth. Oftentimes it is desired to support a construction unit such as a bricklaying machine or the like at the end of a boom or arm and positioned the terminal portion of the boom in such manner that it serves as a guide and determines the final form of the structure. Such a technique is particularly advantageous when buildings are constructed from strips or portions of synthetic resinous foam which are adhered together to form the desired configuration.

It is an object of this invention to provide an improved mechanical linkage adapted to position an arm on a desired curved surface.

A further object of this invention is to provide a mechanical linkage which will generate a spherical or nonspherical surface of rotation.

A further object of this invention is to provide an apparatus for the positioning of an operating mechanism in a guided pattern capable of generating a dome-like surface.

These benefits and other advantages in accordance with the present invention are achieved by an apparatus adapted to position an arm on a curved surface of rotation, the apparatus comprising in cooperative combination a base member having a fixed pivot'point, the fixed pivot point having means to secure the base rotatably to a reference surface, the base member so constructed and arranged so as to rotate about the pivot point in a plane generally normal to the axis of the pivot, the base defining a model surface, the model surface being a model of the curvature of at least a portion of the curvature of the cross sectional configuration of a radial section of the desired surface, a first arm, a second arm, a third arm and a fourth arm, the first arm being pivotally connected to the second and fourth arms, the third arm also being pivotally connected to the second and fourth arms at positions remote from the pivotal connections of the first arm to form a quadrilateral figure of a four bar linkage, the first arm pivotally connected to the base member and adapted to pivot in a plane containing the axis of the base member fixed pivot, the first and second arms being disposed generally adjacent the base memher, the third and fourth arms being disposed generally remote from the base member, a model surface follower secured to the second arm and positioned to engage the model surface of the base, the pivotal connections between the four arms having generally parallel axes which Patented August 2, 1966 are parallel to the axis of the pivotal connection of the first arm to the base member.

Further features and advantages of the present invention will become more apparent when the following specification is taken in connection with the drawing wherein:

FIGURE 1 depicts one embodiment of the invention and in FIGURE 2 there is illustrated an alternate embodiment of the invention.

In FIGURE 1 there is illustrated a linkage or apparatus in accordance with the invention generally designated by the reference numeral 10. The apparatus 10 comprises a base member 11 having a pivot 12 affixed to a reference surface or plane 13. A pair of wheels 14 and 15 are affixed to the base 11 and adapted to rotate about an axis passing through the pivot 12 and essentially radially disposed thereto. The wheels 14 and 15 engage the reference surface 13 and provide support for the base 11. The base 11 defines a model surface 17. The model surface 17 is a model of the curvature of a radial section of at least a portion of the radial surface to be generated. A generally circular guide groove or means 18 is also defined by the base 11. A pivot 19 is afiixed to the base 11 and centered on the circular arc of the guide 18. A first arm 21 is pivotally afiixed to the pivot 19. The first arm 21 has a first pivot point 22, a second pivot point 23 which is in operative engagement with the pivot point 19, and a third pivot point 24 comprising a follower 28 which is in operative engagement with the guide 18. A second arm 26 has a first pivot point 27, and a second point pivotally attached to the first arm 21 at the location of the follower 28. 'The second arm 26 also has affixed thereto a model surface follower 29 in operative engagement with the model surface 17. A third arm 30 having a first pivot point 31 and a second pivot point 32 is pivotally attached to the pivot point 27 of the second arm 26 by the second pivot 32 of the arm 30. A fourth arm or boom having a first pivot point 36 and a second pivot point 37 is pivotally attached to the first pivot 22 of the arm 21 by the pivot point 37 and to the first pivot point 31 of the third arm 30 at the pivot point 36. Remote from the pivot points 36 and 37 is disposed an operating means 38 such as a brick laying machine or similar constructional device. Thus the arms 21, 26, 30 and 35 effectively form a four bar linkage or trapezoid and as illustrated in FIGURE 1 a parallelogram. A positioner '41 such as a hydraulic cylinder is pivotally affixed to the first arm 21 by a piston rod end 42. The cylinder 41 is pivotally afifixed to the base 11 by the pivot means 43. In operation of the apparatus 10 of FIGURE 1, movement of the first arm 21 causes positioning of the operating means 38 along a curve which is an enlarged reproduction of the model surface 17 engaged by the follower 29 of the second arm 26. Rotation of the base 11 about the pivot 12 permits the operating means 38 to be positioned on a surface of rotation having a curvature of the model surface. Thus, for example, in the construction of a building the operating means 38 would be positioned initially at the periphery, building elements deposited, the base member 11 rotated about the pivot 12 and a spirally generated structure results when bricks or stripping are secured to each other.

In FIGURE 2 there is illustrated an alternate embodiment of the invention generally designated by the reference numeral 50. The apparatus comprises in cooperative combination a base member 51 having a fixed pivot 52. Rotatably fixed to the base member 51 and remote from the pivot 52 are wheels 54 and 55 which are adapted to rotate about axes generally readily extending from the axis of the pivot 52. The base 51 defines a generally semicircular guide surface or slot 57 lying in a plane containing the axis of rotation of the pivot 52. The base 11 also defines a model surface 58 which has the same general configuration as the are desired to be traced by the apparatus 50. A pivot 60 is afiixed to the base 51 and has an axis generally perpendicularly disposedly to the axis of rotation of the pivot 52 and lies in a plane normal the axis of pivot 52. A first arm 62 is pivotally connected to the pivot 60 at the location 63. The first arm 60 has aflixed thereto a follower 64 adapted to engage the guide surface 57. Pivotally attached to the first arm 62 at the location of the first arm follower 64 is a second arm 66. The second arm 66 has afiixed thereto a model surface follower 68 so constructed and arranged so as to engage the model surface 58, a third arm 70 is pivotally attached to the second arm 66 at a position generally adjacent the model follower 68, a fourth arm 73 is pivotally attached to the first arm 62 and at the pivot 74 disposed remotely from the position 63 and to the third arm 70 by the pivot 76 remotely disposed from the model follower 68. As in the case of the apparatus of FIGURE 1, the first, second, third and fourth arms are pivotally arranged so as to provide a four bar linkage which is essentially a parallelogram. The fourth arm 73 has afiixed thereto an operating means 78 which moves in an are which is a replica of the arc of the surface 58 in a plane containing the axis of the pivot 52. An operating mechanism generally designated by the reference numeral 80 comprising a motor 81, a worm 82 and a worm gear 83, serves to position the first arm 62, the worm 83 is rigidly affixed to the arm 62 as the motor 81 and the worm 82 are secured to the base 51 providing means for positioning the fourth arm 73 and consequently the operating device 78.

Beneficially either of the embodiments of the apparatus in accordance with the present invention are advantageously employed for such applications as the construction of buildings having generally circular cross sections, for the rotation of radiating devices such as those emitting high energy ionizing radiation about a center remote from the apparatus. Also beneficially, such radiation devices as radar antennas are rotated without the necessity of providing large circular tracks or bearings.

As is apparent from the foregoing specification, the apparatus of the present invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. For this reason, it is to be fully understood that all of the foregoing is intended to be merely illustrative and is not to be construed or interpreted as being restrictive or other limiting of the present invention, excepting as it is set forth and defined in the hereto appended claims.

What is claimed is:

1. An apparatus adapted to position an arm on a curved surface of rotation, the apparatus comprising in cooperative combination a base member having a fixed pivot point, the fixed pivot point having means to secure the base rotatably to a reference surface, the base member constructed so as to rotate about the pivot point in a plane generally normal to the axis of the pivot, the base defining a model surface, the model surface being a model of the curvature of at least a portion of the curvature of the cross sectional configuration of a radial section of the desired surface, the base member further defining a :guide means,

a first arm, a second arm, a third arm and a fourth arm, the first arm being pivotally connected to the second and fourth arms, the third arm also being pivotally connected to the second and fourth arms at positions remote from the pivotal connection of the first arm to form a quadrilateral figure of a four bar linkage,

the first arm pivotally connected to the base member to pivot in a plane containing the axis of the base member fixed pivot, the first and second arms being disposed generally adjacent the base member, the third and fourth arms being disposed generally remote from the base member,

a guide means follower secured to the pivotal connection between the first and second arms and positioned to engage the guide means, a model surface follower secured to the second arm and positioned to engage the model surface of the base, the pivotal connections between the four arms having generally parallel axes which are parallel to the axis of the pivotal connection of the first arm to the base member.

2. The apparatus of claim 1, wherein the base member is supported by wheel members rotating about axes generally radially extending from the axis of the fixed pivot.

3. The apparatus of claim 1 including means to position at least one of the arms relative to the base member.

4. The apparatus of claim 1 wherein the guide means and model surface are generally disposed adjacent the fourth arm.

5. The apparatus of claim 1 wherein the guide means and model surface are disposed remote from the fourth arm.

6. The apparatus of claim 1 wherein an operating means is attached to the fourth arm and remotely disposed from the pivots thereof.

7. The apparatus of claim 6 wherein the model surface is a circular arc and the operating means is a source of electromagnetic radiation.

References Cited by the Examiner UNITED STATES PATENTS 2,610,404 9/1952 Compton 3323 2,734,271 2/ 1956 Moriarty 3325 2,881,521 4/1959 Pearson 33-25 FOREIGN PATENTS 442,467 6/1912 France.

MILTON KAUFMAN, Primary Examiner.

D. H. THIEL, Assistant Examiner. 

1. AN APPARATUS ADAPTED TO POSITION AN ARM ON A CURVED SURFACE OF ROTATION, THE APPARATUS COMPRISING IN COOPERATIVE COMBINATION A BASE MEMBER HAVING A FIXED PIVOT POINT, THE FIXED PIVOT POINT HAVING MEANS TO SECURE THE BASE ROTATABLY TO A REFERENCE SURFACE, THE BASE MEMBER CONSTRUCTED SO AS TO ROTATE ABOUT THE PIVOT POINT IN A PLANE GENERALLY NORMAL TO THE AXIS OF THE PIVOT, THE BASE DEFINING A MODEL SURFACE, THE MODEL SURFACE BEING A MODEL OF THE CURVATURE OF AT LEAST A PORTION OF THE CURVATURE OF THE CROSS SECTIONAL CONFIGURATION OF A RADIAL SECTION OF THE DESIRED SURFACE, THE BASE MEMBER FURTHER DEFINING A GUIDE MEANS, A FIRST ARM, A SECOND ARM, A THIRD ARM AND A FOURTH ARM, THE FIRST ARM BEING PIVOTALLY CONNECTED TO THE SECOND AND FOURTH ARMS, THE THIRD ARM ALSO BEING PIVOTALLY CONNECTED TO THE SECOND AND FOURTH ARMS AT POSITIONS REMOTE FROM THE PIVOTAL CONNECTIONS OF THE FIRST ARM TO FORM A QUADRILATERAL FIGURE OF A FOUR BAR LINKAGE, THE FIRST ARM PIVOTALLY CONNECTED TO THE BASE MEMBER TO PIVOT IN THE PLANE CONTAINING THE AXIS OF THE BASE MEMBER FIXED PIVOT, THE FIRST AND SECOND ARMS BEING DISPOSED GENERALLY ADJACENT THE BASE MEMBER, THE THIRD AND FOURTH ARMS BEING DISPOSED GENERALLY REMOTE FROM THE BASE MEMBER, A GUIDE MEANS FOLLOWER SECURED TO THE PIVOTAL CONNECTION BETWEEN THE FIRST AND SECOND ARMS AND POSITIONED TO ENGAGE THE GUIDE MEANS, A MODEL SURFACE FOLLOWER SECURED TO THE SECOND ARM AND POSITIONED TO ENGAGE THE MODEL SURFACE OF THE BASE, THE PIVOTAL CONNECTIONS BETWEEN THE FOUR ARMS HAVING GENERALLY PARALLEL AXES WHICH ARE PARALLEL TO THE AXIS OF THE PIVOTAL CONNECTION OF THE FIRST ARM TO THE BASE MEMBER. 